Children over age of nine have almost grown brains and they need to have a voice. Our civilization United States of America was founded on people who wanted a vote and a voice in our government to England "No taxation without representation" just in August 18, 1920 woman were aloud to vote lets make 2016 and 2020 the years for children to vote
Children are still learning about the world, and learning about what life is really like in other parts of america. Many children aren't exactly interested in voting, or politics in general. If a parent is voting for a specific person, then they will probably make their children vote the same person, as they could easily persuade the child in question that "x is good", not letting any other areas where children can develop their own opinion on the candidate they want to vote, and agreeing just because they trust their parents completely. 18 and beyond are all ages where a person can make their own decisions on their life on who to vote in a system, whether it is a presidential election or a municipal election.
As a person who has worked with kids, I can safely say that 99.9% of children have almost no interest in politics. They're only going to know what their parents and teachers tell them which would lead to a biased opinion. To use America's children as pawns for their parent's desired political agenda is taking advantage of the children.